Having a degree from UTI but not even close to the years of knowledge on this board, I can offer my .02. Fuel injection and volumetric effeciency is key. Modern materials, ie more consistant expansion/contraction rates, less or no contaminants in little or no blowby, VERY effecient PCV etc systems make for an engine that contains each element of it's performance in it's allocated place, with little cross contamination. This allows for for tight tolerances that LAST. The same tolerances are generally required for an engine to function, but deteriorate quickly if cross contaminated or improperly maintained.